Reflective liquid crystal display device having cholesteric liquid crystal color filter

ABSTRACT

A reflective liquid crystal display device includes a first substrate including a display region and a first non-display region, the first non-display region being disposed at a boundary of the display region. A second substrate faces and is spaced apart from the first substrate, the second substrate including a second non-display region corresponding to a portion larger than the first substrate. A light absorption layer is on an inner surface of the first substrate. A cholesteric liquid crystal color filter (CCF) layer is at the display region and the first non-display region is on the light absorption layer. A common electrode is on the CCF layer. An array element is on an inner surface of the second substrate. A light shielding pattern is on the array element, the light shielding pattern corresponding to the CCF layer at the first non-display region. A retardation plate and a polarizing plate are sequentially formed on the outer surface of the second substrate. A liquid crystal layer is interposed between the common electrode and the array element.

This application claims the benefit of Korean Patent Application No.2001-71519, filed on Nov. 16, 2001, which is hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD) device,and more particularly, to a reflective LCD device having a cholestericliquid crystal (CLC) color filter.

2. Discussion of the Related Art

Presently, LCD devices are developed as next generation display devicesbecause of their light weight, thin profile, and low power consumptioncharacteristics. In general, an LCD device is a non-emissive displaydevice that displays images using a refractive index differenceutilizing optical anisotropy properties of liquid crystal material thatis interposed between an array (TFT) substrate and a color filter (C/F)substrate. Among the various type of LCD devices commonly used, activematrix LCD (AM-LCD) devices have been developed because of their highresolution and superiority in displaying moving images. The AM-LCDdevice includes a thin film transistor (TFT) per each pixel region as aswitching device, a first electrode for ON/OFF, and a second electrodeused for a common electrode.

FIG. 1 is a perspective view of an LCD device according to the relatedart.

In FIG. 1, first and second substrates 10 and 30 are arranged to faceeach other with a liquid crystal material layer 50 interposedtherebetween. On an inner surface of the first substrate 10, a colorfilter (C/F) layer 12 and a common electrode 16, which functions as oneelectrode for applying an electric field to the liquid crystal layer 50,are subsequently formed. The C/F layer 12 includes a color filter fortransmitting only light of a specific wavelength, and a black matrix(not shown) that is disposed at a boundary of the color filter andshields light of a region in which alignment of the liquid crystalmaterial is uncontrollable. On an inner surface of the second substrate30, a plurality of gate lines 32 and a plurality of data lines 34 areformed in a matrix array. A TFT “T”, which functions as a switchingdevice, is disposed at a region where each gate line 32 and data line 34crosses, and a pixel electrode 46 that is connected to the TFT “T” isdisposed at a pixel region “P” defined by the region where the gate anddata lines 32 and 34 cross. First and second polarizing plates 52 and54, which transmit only light parallel to a polarizing axis, aredisposed on an outer surface of the first and second substrates 10 and30, respectively. An additional light source such as a backlight, forexample, is disposed below the second polarizing plate 54.

The LCD device of FIG. 1 is a transmissive LCD device that displaysimages by transmitting only desired light through the first substrateusing an optic/dielectric anisotropy of the liquid crystal layer afterlight from the backlight passes through the second substrate.

FIG. 2 is a schematic plan view of an LCD device according to therelated art. FIG. 2 shows gate and data pads for connection with anexternal circuit.

In FIG. 2, a liquid crystal panel 60 for an LCD device includes a firstsubstrate 10, a second substrate 30 larger than the first substrate 10,and a liquid crystal layer 50 interposed between the first and secondsubstrates 10 and 30. The liquid crystal panel 60 can be divided into adisplay region “D,” and first and second non-display regions “N1” and“N2” in plan view. The first non-display region “N1” is defined by thefirst and second substrates 10 and 30, and the second non-display region“N2” is defined by a larger portion of the second substrate 30. Elementssuch as a TFT, gate and data lines, a pixel electrode, a color filterlayer and a common electrode illustrated in FIG. 1 are formed in thedisplay region “D.” Gate and data pads 62 and 64 connected to anexternal circuit (not shown) are formed in the second non-display region“N2” to apply a display signal to the display region “D.” Since a blackmatrix 66 formed in the first non-display region “N1” of the firstsubstrate 10 absorbs incident light, a boundary of the display region“D” maintains a black state.

FIG. 3 is a schematic cross-sectional view of an LCD device according tothe related art. A boundary of a display region is mainly shown in FIG.3.

In FIG. 3, a boundary of first and second substrates 10 and 30 with aliquid crystal layer 50 therebetween is sealed with a seal pattern 68. Acolor filter layer 40 on an inner surface of the first substrate 10 isextended to a first non-display region “N1” so that a deterioration at aboundary of a display region “D” by a step difference between thedisplay region “D” and the first non-display region “N1” can beprevented during a rubbing process for aligning the liquid crystal layer50. Array elements 42 such as a TFT and a pixel electrode (of FIG. 1)are formed on an inner surface of the second substrate 30. When light isemitted into the first non-display region “N1,” a black matrix 66 of thefirst non-display region “N1” absorbs the light. Accordingly, a blackstate is maintained in the boundary of the display region “D.”

Reflective LCD devices without a backlight are being researched anddeveloped. Transflective LCD devices use a backlight to provide light.However, only about 7% of the light that is emitted by the backlightpasses through each cell of the LCD device. Since the backlight shouldemit light of a relatively high brightness, corresponding powerconsumption increases. Accordingly, a large capacity heavy battery iscommonly used to supply sufficient power for the backlight. Moreover,use of the large capacity battery limits operating time. On the otherhand, because power consumption of the reflective LCD devices greatlydecreases due to use of ambient light as a light source, operating timeincreases. Such reflective LCD devices are used for portable informationapparatuses such as electronic diaries and personal digital assistants(PDAs). In the reflective LCD devices, a pixel area, which is coveredwith a transparent electrode in conventional transmissive LCD devices,is covered with a reflective plate or reflective electrode having opaquereflection characteristics.

However, brightness of reflective LCD devices is very poor because thedevices use only ambient light as a light source. The poor brightnessresults from operational characteristics of the reflective LCD devicesin which ambient light which passes through a color filter substrate, isreflected on a reflective electrode on a second substrate, is passedthrough the color filter substrate again and then displays an image.Accordingly, brightness is decreased as a result of reduction of thetransmittance when the ambient light passes through a color filter layertwice. Since overall thickness of the color filter layer is inverselyproportional to transmittance and is directly proportional to colorpurity of the light, the problem of inadequate brightness of thereflective LCD devices can be remedied by forming a thin color filterlayer with high transmittance and low color purity. However, there is alimit in fabricating the color filter layer below a threshold thicknessdue to characteristics of the resin used to form the color filter layer.

Accordingly, one possible solution to this problem is fabricating LCDdevices using cholesteric liquid crystal (CLC) that has selectivereflection and transparency characteristics. In reflective LCD devicesusing a CLC color filter (CCF) layer, the fabrication processes aresimplified due to omission of the reflective layer, and high colorpurity and high contrast ratio are achieved. Moreover, since CLC has aspiral structure and spiral pitch determines a selective reflectionbandwidth of the CLC, the reflection bandwidth can be controlled by adistribution of the spiral pitch at one pixel. To illustrate this inmore detail, a wavelength range of visible light is from about 400 nm toabout 700 nm. The wavelength of the red light region is centered atabout 650 nm, the wavelength of the green light region is centered atabout 550 nm, and the wavelength of the blue light region is centered atabout 450 nm. The CCF layer is formed having characteristics that canselectively reflect or transmit right-handed or left-handed circularlypolarized light at a bandwidth that corresponds to a pitch deviation byselecting bandwidths corresponding to the red, green, and blue lightregions. In addition, the CCF layer is formed having characteristicsthat control conditions for right or left pitch deviations with respectto the center wavelength. Accordingly, the pitch of the liquid crystalcan be artificially adjusted so that a CCF layer can selectively reflectlight of an intrinsic wavelength of the color corresponding to eachpixel.

FIG. 4 is a schematic plan view of a reflective LCD device using a CCFlayer according to the related art. FIG. 4 shows gate and data pads forconnection with an external circuit.

In FIG. 4, since the reflective LCD device using a CCF layer displaysimages by reflecting ambient light, array elements (not shown) and a CCFlayer are formed on first and second substrates 70 and 72, respectively.Accordingly, the first substrate is larger than the second substrate 72.As a result, even though a display region “D” is disposed as in the LCDdevice of FIG. 3, a first non-display region “N1” corresponds to aboundary of the second substrate 72 and a second non-display region “N2”corresponds to a larger portion of the first substrate 70. Especially,even though a black matrix is disposed at the first non-display regionadjacent to the display region in the LCD device of FIG. 3, anadditional black matrix between adjacent pixels is omitted due to aselective reflection property of the CCF layer and a metal bar 78 of onematerial of a gate pad 74 and a data pad 76 is disposed at the firstnon-display region “N1” not adjacent to the second non-display region“N2” to prevent light reflection in the reflective LCD device using aCCF layer. However, an extra metal bar to prevent light reflection isnot disposed at the first non-display region “N1” adjacent to the secondnon-display region “N2” where the gate pad 74 and the data pad 76 areformed.

FIG. 5 is a schematic cross-sectional view of a reflective LCD deviceusing a CCF layer according to the related art. A boundary of a displayregion is mainly shown in FIG. 5.

In FIG. 5, a first substrate 70 including array elements 86 and a secondsubstrate 72 including a CCF layer 82 face each other. Incident lightinto the CCF layer 82 displays colors by the CCF layer 82 whose pitch isadjusted according to a wavelength of each color. These colorsconstitute desired images by a refractive index difference at a liquidcrystal layer (not shown) interposed between the first and secondsubstrates 70 and 72. To illustrate this in more detail, the arrayelements 86 are formed on an inner surface of the first substrate 70 anda light absorption layer 80 is formed on an entire inner surface of thesecond substrate 72. The CCF layer 82 is formed at a display region “D”and a first non-display region “N1” on the light absorption layer 80. Acommon electrode 84 is formed on the light absorption layer 80 and theCCF layer 82. The array elements 72 on the second substrate 30 of FIG. 3can be used as the array elements 86.

When external light enters the CCF layer 82 at the first non-displayregion “N1,” the CCF layer 82 reflects a circularly polarized light suchas left-handed or right-handed circularly polarized lights and thecircularly polarized light is emitted to an exterior without passingthrough an additional light shielding layer. Accordingly, brightnessundesirably increases at a boundary of the display region and a displayquality of the reflective LCD device decreases.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a reflective liquidcrystal display device that substantially obviates one or more ofproblems due to limitations and disadvantages of the related art.

An advantage of the present invention is to provide a reflective liquidcrystal display device of high display quality using a cholestericliquid crystal color filter layer by reducing brightness at a boundaryof a display region.

Another advantage of the present invention is to provide a reflectiveliquid crystal display device including a light shielding patterncorresponding to a cholesteric liquid crystal color filter layer at anon-display region of a lower substrate.

Additional features and advantages of the invention will be set forth inthe description that follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, areflective liquid crystal display device includes: a first substrateincluding a display region and a first non-display region, the firstnon-display region being disposed at a boundary of the display region; asecond substrate facing and spaced apart from the first substrate, thesecond substrate including a second non-display region corresponding toa portion larger than the first substrate; a light absorption layer onan inner surface of the first substrate; a cholesteric liquid crystalcolor filter (CCF) layer at the display region and the first non-displayregion on the light absorption layer; a common electrode on the CCFlayer; an array element on an inner surface of the second substrate; alight shielding pattern on the array element, the light shieldingpattern corresponding to the CCF layer at the first non-display region;a retardation plate and a polarizing plate sequentially formed on theouter surface of the second substrate; and a liquid crystal layerinterposed between the common electrode and the array element.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments of the invention andtogether with the description serve to explain the principle of theinvention.

In the drawings:

FIG. 1 is a perspective view of an LCD device according to the relatedart;

FIG. 2 is a schematic plan view of an LCD device according to therelated art;

FIG. 3 is a schematic cross-sectional view of an LCD device according tothe related art;

FIG. 4 is a schematic plan view of a reflective LCD device using a CCFlayer according to the related art;

FIG. 5 is a schematic cross-sectional view of a reflective LCD deviceusing a CCF layer according to the related art;

FIG. 6 is a schematic plan view of a reflective LCD device using a CCFlayer according to an embodiment of the present invention;

FIG. 7 is a schematic cross-sectional of a reflective LCD deviceaccording to an embodiment of the present invention;

FIG. 8 is a flow chart illustrating a fabricating process of a substrateincluding a light shielding pattern according to an embodiment of thepresent invention;

FIG. 9 is a schematic plan view of a reflective LCD device using a CCFlayer according to another embodiment of the present invention;

FIG. 10 is a schematic plan view of a reflective LCD device using a CCFlayer according to another embodiment of the present invention; and

FIG. 11 is a schematic cross-sectional view of a reflective LCD deviceusing a CCF layer according to another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, example of which is illustrated in the accompanying drawings.Wherever possible, the same reference numbers will be used throughoutthe drawings to refer to the same or like parts.

FIG. 6 is a schematic plan view of a reflective LCD device using a CCFlayer according to an embodiment of the present invention. A boundary ofa display region is shown in FIG. 6.

In FIG. 6, a liquid crystal panel 160 includes a first substrate 110, asecond substrate 130 smaller than the first substrate 110 and a liquidcrystal layer 150 interposed between the first and second substrates 110and 130. The liquid crystal panel 160 can be divided into a displayregion “D,” and first and second non-display regions “N1” and “N2” inplan view. The first non-display region “N1” is adjacent to a boundaryof the display region “D” and is defined by the first and secondsubstrates 110 and 130. The second non-display region “N2” correspondsto a larger portion of the first substrate 110. A gate pad 152 and adata pad 154 are disposed at the second non-display region “N2” of thefirst substrate 110. Moreover, a light shielding pattern 104 adjacent tothe display region “D” is disposed at the first non-display region “N1.”The light shielding pattern 104 is made of an organic material absorbinglight. The light shielding pattern 104 is formed not through anadditional process but through a process of forming a black matrix (notshown) that prevents light from entering a switching element (not shown)on the first substrate 110.

FIG. 7 is a schematic cross-sectional of a reflective LCD deviceaccording to an embodiment of the present invention. A boundary of adisplay region is mainly shown in FIG. 7.

In FIG. 7, a first substrate 110 and a second substrate 130 face and arespaced apart from each other. A light absorption layer 132 is formed onan inner surface of the second substrate 130 and a CCF layer 134 isformed on the light absorption layer 132 at a display region “D” and afirst non-display region “N1.” A common electrode 136 is formed on theCCF layer 134 and the light absorption layer 132. Array elements 102 areformed on an inner surface of the first substrate 110 and a lightshielding pattern 104 is formed on the array elements 102 at the firstnon-display region “N1” adjacent to the display region “D.” A protectionlayer 106 is formed on the light shielding pattern 104 and the arrayelements 102. The protection layer 106, which covers the array elements102, is different from a passivation layer for a TFT in that theprotection layer 106 functions as a buffer layer between the lightshielding pattern 104 and a liquid crystal layer 150. A retardationplate 108 and a polarizing plate 109 are sequentially formed on an outersurface of the first substrate 110. The polarizing plate 109 is a linearpolarizing plate transmitting only light parallel to a polarization axisof the polarizing plate 109 and the retardation plate 108 is a quarterwave plate (QWP) whose slow axis makes one angle of +45° and −45° withrespect to the polarization axis. The slow axis is defined by adirection parallel to the direction along which the refractive index ofthe QWP is larger than along any other direction. The QWP transformslinearly polarized light into circularly polarized light by aretardation value of λ/4, and vice versa. When the slow axis makes anangle of +45° with respect to the polarization axis, the QWP transformslinearly polarized light into left-handed circularly polarized light. Onthe other hand, when the slow axis makes an angle of −45° with respectto the polarization axis, the QWP transforms linearly polarized lightinto right-handed circularly polarized light. Furthermore, a sealpattern 152 is formed at the first non-display region “N1” to attach thefirst and second substrates 110 and 130.

Light passing through each cell at the boundary of the display region“D” of the reflective LCD device using the CCF layer is illustrated indetail with an assumption that the CCF layer 134 selectively reflectsonly a right-handed circularly polarized light and the retardation plate108 has a slow axis making an angle of −45° with respect to thepolarization axis. External light is transformed into linearly polarizedlight for passing through the polarizing plate 109 and the linearlypolarized light is transformed into right-handed circularly polarizedlight for passing through the retardation plate 108. Since theright-handed circularly polarized light is absorbed into the lightshielding pattern of a material absorbing light, a black state isobtained. Accordingly, a white phenomenon at the boundary of the displayregion can be prevented.

FIG. 8 is a flow chart illustrating a fabricating process of a substrateincluding a light shielding pattern according to an embodiment of thepresent invention.

At step ST1, after a first metallic material is deposited on asubstrate, a gate line including a gate electrode and a gate pad isformed through a photolithography including exposure, development andetch processes.

At step ST2, after silicon nitride (SiNx), amorphous silicon (a-Si) andimpurity-doped amorphous silicon (n+ a-Si) are sequentially deposited onan entire surface of the substrate, the a-Si and the n+ a-Si are etchedthrough a photolithography to form an active layer and an ohmic contactlayer, respectively. The SiNx functions as a gate insulating layer. Theactive layer and the ohmic contact layer constitute a semiconductorlayer.

At step ST3, after a second metallic material is deposited on an entiresurface of the substrate, a data line including source and drainelectrodes spaced apart from each other is formed through aphotolithography. In this step, a channel is formed through exposing theactive layer between the source and drain electrodes. Thus, a thin filmtransistor (TFT) including the gate electrode, the semiconductor layer,and the source and drain electrodes is completed.

At step ST4, a passivation layer is formed on the TFT, the gate line andthe data line through depositing or coating a material for thepassivation layer. The passivation layer has a drain contact holeexposing the drain electrode through a photolithography.

At step ST5, a black matrix and a light shielding pattern are formed onthe passivation layer. The black matrix and the light shielding patterncorrespond to the TFT and a first non-display region adjacent to adisplay region, respectively.

At step ST6, after an organic insulating material is coated on the blackmatrix and the light shielding pattern, a protection layer having acontact hole corresponding to the drain contact hole is formed through aphotolithography.

At step ST7, after a transparent conductive material is deposited on theprotection layer, a pixel electrode is formed through aphotolithography. The pixel electrode is connected to the drainelectrode through the drain contact hole. Moreover, an orientation filmis formed on the pixel electrode to align a liquid crystal layer.

FIG. 9 is a schematic plan view of a reflective LCD device using a CCFlayer according to another embodiment of the present invention.Illustrations for the same portion as the reflective LCD device of FIG.6 will be omitted.

In FIG. 9, a plurality of light shielding patterns 202 are formed at afirst non-display region “N1” adjacent to a second non-display region“N2.” The plurality of light shielding patterns 202 are made of the samematerial as a gate pad 152 and a data pad 154. Here, the plurality oflight shielding patterns 202 adjacent to a display region “D” prevent awhite phenomenon of a boundary of the display region “D.” If theplurality of light shielding patterns 202 cover a gate line and a dataline (not shown), a parasitic capacitor degrading a display quality canbe generated between the plurality of light shielding patterns 202 andthe gate and data lines. Accordingly, the plurality of light shieldingpatterns 202 are formed at spaces between the adjacent gate lines andbetween the adjacent data lines. However, if the plurality of lightshielding patterns 202 are formed exactly at the spaces between the gatelines and between the data lines, a light leakage can occur in the caseof misalignment. Therefore, the plurality of light shielding patterns202 overlap the gate and data lines within a range of about 1 μm toabout 3 μm to maintain a black state at the boundary of the displayregion “D.” Moreover, the plurality of light shielding patterns 202 aremade of the same material as the data line at the space between the gatelines, and made of the same material as the gate line at the spacebetween the data lines to prevent an electric short between theplurality of light shielding patterns 202 and the gate and data lineswithout an additional process. A metal bar 204 of one material of thegate pad 152 and the data pad 154 is disposed at the first non-displayregion “N1” not adjacent to the second non-display region “N2” toprevent light reflection in the reflective LCD device using a CCF layer.

As in the reflective LCD device of FIG. 6, under the assumption that theCCF layer (not shown) selectively reflects only a right-handedcircularly polarized light and the retardation plate (not shown) has aslow axis making an angle of −45° with respect to a polarization axis,external light is transformed into linearly polarized light for passingthrough the polarizing plate and the linearly polarized light istransformed into right-handed circularly polarized light for passingthrough the retardation plate. Since the right-handed circularlypolarized light is absorbed into the light shielding pattern of the samematerial as the gate and data lines, a black state is obtained.Accordingly, a white phenomenon at the boundary of the display regioncan be prevented.

FIG. 10 is a schematic plan view of a reflective LCD device using a CCFlayer according to another embodiment of the present invention.Illustration for the same portion as the reflective LCD device of FIG. 9will be omitted.

In FIG. 10, a light shielding pattern 302 of a transparent conductivematerial is formed at a first non-display region “N1” adjacent to adisplay region “D.” The light shielding pattern 302 is simultaneouslyformed with a pixel electrode using the same material as the pixelelectrode. Moreover, the light shielding pattern 302 may be electricallyisolated from the pixel electrode. Instead, the light shielding pattern302 may be connected to a common electrode (not shown) of a secondsubstrate (not shown) through a silver (Ag) dot point for an electricconnection between first and second substrates. Accordingly, a samesignal is applied to the light shielding pattern 302 and the commonelectrode.

FIG. 11 is a schematic cross-sectional view of a reflective LCD deviceusing a CCF layer according to another embodiment of the presentinvention. Illustration for the same portion as the reflective LCDdevice of FIG. 7 will be omitted.

In FIG. 11, since a same signal is applied to a light shielding pattern302 at a first non-display region “N1” adjacent to a display region “D”and a common electrode 136 over a second substrate 330, a liquid crystallayer 150 between the light shielding pattern 302 and the commonelectrode 136 functions as a π-cell to have a retardation of λ/2.

As in the reflective LCD device of FIG. 7, under the assumption that aCCF layer 134 selectively reflects only a right-handed circularlypolarized light and the retardation plate 108 has a slow axis making anangle of −45° with respect to a polarization axis of a polarizing plate109, external light is transformed into linearly polarized light forpassing through the polarizing plate 109 and the linearly polarizedlight is transformed into right-handed circularly polarized light forpassing through the retardation plate 108. Since the right-handedcircularly polarized light is transformed into a left-handed circularlypolarized light for passing through the liquid crystal layer 150 havinga retardation of λ/2, the left-handed circularly polarized light isabsorbed into a light absorption layer 132 under the CCF layer 134 atthe first non-display region “N1.” Accordingly, a black state isobtained at a boundary of the display region “D” and a white phenomenonat the boundary of the display region “D” is effectively prevented.

Consequently, since a light shielding pattern is included in areflective LCD device using a CCF layer according to the presentinvention, a black state is kept at a boundary of a display region and adisplay quality is improved.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1-27. (Canceled)
 28. A method of manufacturing a reflective liquidcrystal display device, comprising: providing a first substrateincluding a display region and a first non-display region, the firstnon-display region being disposed at a boundary of the display region;forming a light shielding pattern of a transparent conductive materialat the first non-display region adjacent to the display region, whereinthe light shielding pattern is simultaneously formed with a pixelelectrode using the same material as the pixel electrode; forming alight absorption layer on an inner surface of the first substrate;forming a cholesteric liquid crystal color filter (CCF) layer at thedisplay region and the first non-display region on the light absorptionlayer; applying a same signal to the light shielding pattern at thefirst non-display region adjacent to the display region and a commonelectrode over a second substrate; forming a liquid crystal layerbetween the light shielding pattern and the common electrode, whereinthe liquid crystal layer is a π-cell having a retardation of λ/2. 29.The method according to claim 28, wherein the light shielding pattern iselectrically isolated from the pixel electrode.
 30. The method accordingto claim 28, wherein the light shielding pattern is connected to acommon electrode of a second substrate through a silver (Ag) dot pointfor an electric connection between the first and second substrates.